Few would have paid much attention to the two young black men surveying the landscape around Parliament Square in 1962, but it was then that Oliver Tambo and his friend Nelson Mandela joked about what must have seemed a preposterous notion. "We hoped that one day a statue of a black person would be erected here" alongside that of the former South African leader General Jan Smuts, Mr Mandela recalled yesterday.

Oliver Tambo never lived to see their hope come to fruition, but as the morning sun beamed down yesterday, Mr Mandela returned to Parliament Square to see 7,000 people and the unveiling of a statue of a black man sharing space with the general, Winston Churchill and Abraham Lincoln, not to mention the Commons, the Lords and Westminster Abbey.

Mr Mandela, now 89, accepted that the figure, 2.7 metres (9ft) tall and clad in a flowered shirt, with arms outstretched, was a likeness of him.

But the former South African president and Nobel prize winner said it spoke to something greater. "Although this statue is of one man it should in actual fact symbolise all those who have resisted oppression, especially in my country," he said. "The history of the struggle in South Africa is rich with the stories of heroes and heroines, some of them leaders, some of them followers. All of them deserve to be remembered. We thank the British people once again for their relentless efforts in supporting us during the dark years."

He said the statue and its siting would have pleased his friend, who became president of the ANC. "Oliver would have been proud to have been here."

The mere presence of Madiba - Mr Mandela's Xhosa clan title - appears to bring healing qualities. The project began seven years ago and was dogged by rows between Ken Livingstone, who wanted the statue sited in Trafalgar Square, and Westminster council, which deemed it inappropriate for that space, and between Ian Walters, the sculptor, who has since died, and others in the art establishment who said the statue was not good enough for display.

When the project began, Mr Livingstone and Gordon Brown were barely on speaking terms. But yesterday, as Mr Mandela looked serenely at the dignitaries in front of him and the noisy, adoring crowd in the middle distance, there was a harmony hitherto unthinkable.

Mr Livingstone said the project was the brainchild of Donald Woods, the journalist and anti-apartheid activist. On the death of Mr Woods, responsibility passed to his widow, Wendy, and his friend Lord Attenborough. Though Trafalgar Square was the mayor's preference, he told Mr Mandela that there could be "no more fitting place than this square which you will share with the American president who freed the slaves and the British prime minister who led a nation standing alone against the evil of Nazi ideology".

Mr Brown sat to Mr Mandela's right on the podium and when he spoke it was with an intensity rarely witnessed in the Commons. On behalf of Britain, he hailed "the man who will be remembered forever as the leader who ended apartheid". The superlatives flowed quickly. "The man whom no prison cell, no intimidation, no show trial, no threat of execution could ever silence," he said. "The man whose belief in the future was so powerful that not even 27 years behind bars and barbed wire could destroy his dream and his demand that by fighting apartheid from his prison cell millions today could be and are free."

Mr Brown was cheerleader and helper to Mr Mandela, whose face is relatively youthful but whose legs are now weak. The prime minister helped the guest of honour, who used a cane, to and from the podium. Earlier, when the cloth was pulled from the statue, exposing it to the elements and the crowd's gaze for the first time, Mr Mandela applauded but remained in his seat. Everyone else stood.

His wave to the crowd seemed designed to save energy, a slow-motion windscreen wiper action, but his voice was comparatively strong. He revealed that a Live Aid-style concert for his anti-Aids charity 46664 - named after his prisoner number on Robben Island - would be staged at Hyde Park next June. "I hope very much to be back in London to attend and I hope to see you there," he said.

David Cameron sat at the front as did the Rev Jesse Jackson, who flew in from Chicago yesterday morning. The Milibands sat close to Ming Campbell, John Prescott, Lord Owen, Lady Williams and Ben Okri. Naomi Campbell sat in the sun as did Brian May, the Queen guitarist, now Mr Mandela's concert organiser.

Tony Benn recalled how in 1960 he tabled the first motion calling for a boycott of apartheid South Africa. "If Diana was the people's princess," he said, "Nelson Mandela is president of the human race."